1. Field of the Invention
The present invention relates to a rectifier for an alternator for use in an automotive vehicle.
2. Description of Related Art
A conventional rectifier 5 for an automotive alternator 1 is shown in FIGS. 5-7. As shown in FIG. 5, the rectifier 5 includes a positive heat-sink plate 51, a negative heat-sink plate 52, a terminal base 55, a rectifier terminal 257, a resin spacer 58 and other associated components. As shown in FIGS. 6 and 7, a positive rectifier element 53 is inserted into a through-hole 83 of the positive heat-sink plate 51, and a negative rectifier element 54 inserted into a through-hole 83 of the negative heat-sink plate 52. Lead wires 531, 541 are soldered to the rectifier elements 53, 54, respectively, and the soldered portions are sealed by respective sealing portions 61.
The rectifier terminal 257 is connected by molding to the terminal base 55 having a cylindrical portion 62 through which a bolt 59 is inserted. The negative heat-sink plate 52, the resin spacer 58, the positive heat-sink plate 51 and the terminal base 55 are laminated in this order and fixed to a rear housing 42 by the bolt 59 and a nut 60. A rectifier terminal 257 is connected by welding to the lead wire 531 of the positive rectifier element 53, and another rectifier terminal 257 is connected by welding to the lead wire 541 of the negative rectifier element 54. Further, a portion of the rectifier terminal 257 is connected by welding to a stator lead 23 constituting a phase terminal of a stator coil 22. The rectifier 5 is cooled by a rear fan 37 connected to a rear side of a rotor 3.
Since the sealing portion 61 of the rectifier elements 53, 54 is not covered with the rectifier terminal 257 in the conventional rectifier 5 described above, cooling air containing moisture and salt is directly blown to the sealing portion 61 formed by resin or rubber. Therefore, there has been a problem that the sealing portion 61 is deteriorated by the moisture and the salt contained in the cooling air. Heat generated by welding in a process of connecting the lead wires 531, 541 to the rectifier terminals 257 is transferred to the heat-sink plates 51, 52. However, a size of the rectifier terminal 257 of the conventional rectifier is not large enough to sufficiently dissipate the heat and to protect rectifier elements 53, 54 from the welding heat. Therefore, a heat-dissipating jig is attached to the lead wires 531, 541 in the welding process to enhance heat dissipation. Attaching the heat-dissipating jig to the lead wires 531, 541 requires an additional step in the welding process. This has been another problem involved in the conventional rectifier. Further, it has been troublesome to correctly position the lead wires 531, 541 relative to the rectifier terminal 257 in the welding process, because the rectifier terminal 257 is plate-shaped and has no hole for inserting the lead wires 531, 541.